The LNER Encyclopedia

John Palmer wrote: ↑Sun May 26, 2019 1:03 am Details to be found at p114-115 in Vol. 6A of the RCTS series on LNER locomotives.

The casings enclose the feed water pipes to a top feed ahead of the dome, fitted in connection with a Gresham & Craven feedwater heater. It would seem, from the RCTS description, that the casings enclose asbestos lagging of the feed water pipework to prevent heat loss, but I am unclear as to why such lagging would be required if the feedwater heater was mounted within the casing that can be seen straddling the top of the boiler. Perhaps the intention was to limit the loss of heat already imparted to the feedwater by the injectors mounted on the boiler backplate.

The valve beneath the transverse casing apparently forms part of the Hulburd blowdown apparatus also fitted to this engine, manually operated on the fireman's side by the linkage visible in the picture.

The fitting on the top of the boiler behind the dome is likely to form part of the Gunderson foam indicating apparatus also applied to this locomotive. Some further details of this, including the relevant US patent application, can be found by following the hyperlinks at this URL: http://www.rypn.org/forums/viewtopic.php?f=1&t=33974

(Edited to add that the discoloration on the side of the boiler beneath the Hulburd valve probably results from sludge leaking by the gland through which the control rod to the valve passes)